Process for making grids



July 30, 1957 F. WARNER ETAL 2,800,929

PROCESS FOR MAKING GRIDS Filed Nov. 16, 1953 SSheets-Sheet 1 INVENTORS.

FRED WARNER. LENDON L. CALHOUN.

.mms E. HERBE. 2 9 BY aw X9. QWJZ ATTORNEYS.

July 30, 1957 F. WARNER ET AL 2,800,929

PROCESS FOR MAKING GRIDS Filed Nov. 16, 1953 3 Sheets-Sheet 2 INVENTORS.

. FRED WARNER.

L 0N L. CALHOUN.

' MES E. HERBE.

BY MW I A ORN YS.

July 30, 1957 Filed NOV. 16, 1953 F. WARNER ET AL PROCESS FOR MAKING GRIDS 5 Sheets-Sheet 5 FRED WARNER.

LENDON L. CALHOUN.

JAMES E. HERBE.

BY Wm! @W fi iiqfgy.

AT ORNEYS.

United States Patcfi o r 2,800,929: PROCESSLFORIYMAKINGGRIDS'V- 1 Claim.. (Cl. 140-715) This invention relates generally 'tofa process-for winding grid elements for electron tubes and, more specifically; to a grid winding process and structure suitable for use in fabricating a color selecting shadow masking gridlfor a cathoderray tube 'of the 'type, having a multi-colored phosphor screen. v

The Wire gridjo'r .grid's' in a'conventional electron receiving tubev of theltriode, tetrod'e or. pentode 'type are wound on'a 'varietyof 'comm'ercial'machines which have beendeveloped solely, for fabricating such grids. However, in thecathod'e-ray 'tube-art'thc conventional grids, a'sfar as black and white tubes are concerned,'are not made of wire. Instead, they comprise a portion of 'the electron gun and take "the 'form of'ape'rtured cup-like or tubular elements.

With the adventjofcatliode-ray tubes suitable for rey 2,800,929 I Patented July 30, 195? a winding mandrelll, preferably tubular in form, which is driven by. a conicahdrive means 12 from either shaft '13 or 16"with 'the'other cone andshaft acting as a dead center. As can be seen from the. 'schematic'thread designation. shown on mandrel 11in Fig. 1, the winding mandrel is threaded at :a". selectedpitch. Selection of this pitch is governed by the spacing desired between grid wires in the finished grid element.

For example, ifthe gridwiresare to be evenly spaced, then mandrel 11 should be provided with threads having a uniform pitch, withfthre'ad groove spacingequal to the desiredv grid wire spacing. If, on the other hand, the finished grid element isit'o have non-uniform wire spacing, then it isnecess'ary that th'e'winding mandrel thread pitch be non-uniform in'tlie desiredrnanner. In other words;

. if the spacing'betweengridwiresnear the top and bottom ofthegrid element i sl'to' be greater than the spacing between the grid wiresneariand at the center of the grid element, it followsthat the thread pitch of the end portions of winding mandre'll'l' should be greater than the thread pitchneartlie"center'of the mandrel.

producingvimagesjin color, various structures have been 'su"ggested"which' require wire type color selecting or shadow masking grids to be positioned adjacent the phosphor screen.. .Atpresentzfew, if fillYySllChillbCS .are being produced in commercial quantities, and the grid winding structures or"machinessuitable for'fabricating grids of the required; type. cambefound only'in the laboratory. Since it. is now obvious that cathode rayitubes of -the-color type will .soon be. producedin. commercial quantities in orderyto satisfy. thegrowingdemandiof the public for color television .receivers,..it would :be desirable to provide a grid winding. structureand'process suitable for producing colorgrids in-large quantities-.

Thus, itbecomesan object of thisiinvention do provide a relativelyt simple grid. windingxprocess suitable for winding large. grids incommercial quantities.

Briefly, the inventioncomprisesraiprocess for. feeding grid wire on. to.amandrel.whichisrthreaded to space the received wire'at the..desired..grid.1pitcli; :i. e., either a uniform pitch-.or anon-uniformpitch; .Means are-also-provided. iforxdixedlyattachingthewi'res to: mounting strips and for cutting the finished grid element from the mandrel.

For a better understanding of the present invention, together with other and further objects, advantages and capabilities thereof, reference is made to the following disclosure and appended claim in connection with the accompanying drawings, in which:

Fig. 1 illustrates the complete grid winding structure;

' and Fig. 2 illustrates the winding mandrel, in broken view,

partially filled with grid wire; and

Fig. 1 shows a simple form of the invention comprising Feed screw l fismade torotate' at the same speed as the winding mandrel 11'.in" orde'r'to drive the engaged support 15., shown diag'lammatically' in Fig. 1 in block form, along "the longitudinal axis ofthe'winding mandrel 11'. Wire'guide" 1'1',,which maybe tubular in shape, as shown'in Fig. '1, or which mayta'ke; any'other shape suit= able 'forgnidingwire 18into.the"lthread grooves on winding"ma1 1d'rel 11, is fixedly attached to -wire guide support15'. v 7

As 'can'bestbeseen in'Fig; 1; wire guide 117 progresses alongthe 'long'itudinal'iaiiis of winiling mandrel 11 so asto' lay the :grid"wire 1'8 in the'bottom of thethread groovesofmand'relil, making it necessary that the driving 'feed screw' 1'4fhave exactly" the same pitch as the threads on windingman'd'rel 11. For example, if the thread pitch onwindingmandrel 11is uniform, then the thread'pitcli on feed screw 14' must also be uniform. Likewise; in thecasewhere the thread pitch on winding mandrel "11"is"non-funiform, the thread pitch on feed screw1'4 mustbe non=uniform"'in identical manner.

Preferably; wire guide 17 should carry' the wire in close proximity to "thegrooved surface on winding mandrel 11' so 'thafmaximum advantage can be obtained from the use of t'hreaded feed screw, and the wire fed into the" mandrel "grooves" with approximately .the correct spacing. Final accuracy is' obtained by virtue of the spacing between'threadgrooves on the mandrel surface. If the grooves are accurately spaced, then. the grid wires restingin-thebottom of the thread grooves will be positioned with equalaccuracy.

A "wire ten'sioningdevice, not shown, may be provided either in wire guide 17, on the wire spool, or between the wire spool and wire guide 17. As best shown in Fig. 2, pegs 19 are provided on the mandrel to function as binding posts for connecting the starting end of the grid wire and for tying off the final end of the grid wire after all the mandrel grooves are filled. As best shown in Fig. 2 and Fig. 4 showing the side of the mandrel not seen in Fig. 1, the mandrel is also provided with positioning pegs 20 which are spaced to receive grid end strips 22. These strips 22 actually comprise a portion of the finished grid frame to which each grid wire is fixedly attached, either by welding, pressure, or some similar fastening means. As can best be seen in Figs. 4, 6 and 7, there are four such end strips required for each grid assembly.

The first pair of grid units strips 22 are placed on positioning pegs 20 before the grid element is wound. As shown in Fig. 4, mandrel 11 is formed to provide a groove or channel on its surface having a longitudinal axis parallel to the lohgitudinal axis of the mandrel. Thus, the two end strips'22, when placed on the mandrel, tend to fill in the channeled portion of the mandrel, making a relatively continuous surface over. which the grid wires are fed. V

The slight curvature of the 'strips 22 in Fig.4 arises from the fact that the pressure of the wire as it is placed on the mandrel is suflicient to bend the strips to conform to the curvature of the mandrel surface. As can be seen from Figs. and 6, end strips 22 return to a flat condition after being removed from the mandrel.

In operation, after a pair of end strip elements 22 are placed in position on the positioning pegs 20, the grid starting end peg 19, as shown in Fig. 2, and the mandrel is rotated by drive cone 12 to feed the wire 18 into the mandrel thread grooves. Since lead screw 14 has the same thread pitch as mandrel 11, wire guide 17 is moved by lead screw 14 at the correct speed for positioning the mandrel end of the wire guide directly over the next mandrel groove into which wire 18 is to be fed. 'When the mandrel is completely filled with wire, the wire is attached to the remaining binding or tie-oflf peg 19 under tension, and then cut between the wire guide 17 andv the tie-ofi binding peg. At this point the two end strips 22 are held tightly in place in the longitudinal mandrel groove, due to thepres'sure of the grid wire.

After the mandrel is removed from the driving cones 12, a second pair of end strips are placed directly over the first pair, on positioning pegs 20. As a result,fthe grid wires are sandwiched between two sets of matching end strips. The assembly is then'run through a seam welder, as shown in Fig. 4, where roller 30 acts as the ground or common electrode-and rollers 31 and 32- the hot electrodes. Metal inlay 34 may-comprise any suit: able electrode material, such as Mallory, Tipaloy, etc. I

wires under tension at all times so that the wires do not become either entangled with each other or knot and break.

The grid element which results from each winding operation, as shown in Fig. 5, may be used in any desired tube where it is permissible to operate all grid wires at a common potential. All grid wires are welded or attached to the metal end strips,- and thus are at a common potential. Thus, in color tubes of the tupeusing a plurality of interleaved grid elements, co-planar or otherwise, where portions of the complete gridare operated at a potential different from the potential of the remainder of the grid,

it will be necessary to use two or more of the grid elewire 18 is fed through wire guide 17 and attached to the ments, as the case may be, of the type shown in Fig. 5 and Fig. 6. p

Of course, if end strips having the properties of an insulator, i. e., having high dielectric constant, are used,

' then it is possible to electrically interconnect the various grid wires as desired, and to make adjacent wires operate at different potentials. Having thus described our invention, we claim:

A process of winding electron tube grid structures i comprising the step of placing a pair of, end strips in parallel spaced relationship on the surface of longitudinal grooves provided in a tubular threaded winding'mandrel, winding grid wire on to said mandrel by spacing each turn to fall into the thread groove, welding said end strips to the grid wire wherever said end strips cross said grid wires by passing one welding electrode along the longitudinal a'xes of the end strips above the mandrel and by passing the other welding electrode along the longitudinal axes ofthe end strips inside the mandrel, cutting the grid wire which extends across said longitudinal mandrel After the unit is taken from the welder, the only operation that remains is to cut the grid from the mandrel. There are many ways in which this cutting operation might be accomplished. One method is shown in Fig. 7, for example, where it can be seen that two slots are formed in mandrel 11 to receive the end strips 22, and H the surface between these two slots is formed to provide a cutting edge. After the mandrel is removed from the welder, a simple cutting blade 37, as shown in Fig. 7, can be run across the wires directly above the cutting edge, and the wires severed, as shown. If desired, cutting edges may be provided which remove all wire extending between the two pairs of end strips. In the absence of such a device, grid wires 18 should .be trimmed, as shown in Fig. 5 and Fig. 6, so as not to extend beyond the end strip 22.

After the wire is out between the grid end pieces, the grid may be removed from the mandrel. Preferably, this should be done in such manner as to keep the grid groove between end strips, and removing the grid wire and fastened end strips from the mandrel while keeping the wire under tension.

References Cited thefile of this patent UNITED STATES PATENTS 434,804 Quiggin Aug. 19, 1890 868,844 Conner Oct. 22, 1907 1,436,322 Sagl Nov. 21, 1922 1,472,505 Trimble Oct. 30, 1923 1,616,947 Bender Feb. 8, 1927 1,934,097 Simon Nov. 7, 1933 2,054,196 Gogan Sept. 15, 1936 2,068,675 Heller Jan. 26, 1937 2,321,780 Tondeur Iune 15, 1943 2,379,135 'Ekstedt June 26, 1945 2,441,228 Schneider May 11, 1948 2,451,360 Skehan Oct. 12, 1948 2,589,503 McCullough Mar. 18, 1952 2,654,401 Legendre Oct. 6, 1953 2,675,773 'Carr Apr..20,1954 

